1. Field of the Invention
The present invention relates to an ink cartridge with a pressure-controlling module, and more particularly, to an ink cartridge with a pressure-controlling module which serves as a buffer to absorb a rapid volume increase in an ink reservoir and controls a negative pressure inside the ink cartridge caused by the use of ink.
2. Description of the Related Art
An ink cartridge used in an ink-jet printer stores ink, ejects ink droplets through a printhead and prints a predetermined color image on a printing medium. FIG. 1 is a cross-sectional view of an ink cartridge disclosed in U.S. Pat. No. 5,409,134. Referring to FIG. 1, a lid 2 is coupled to an ink reservoir 1 of the ink cartridge. A spring 3 and a flexible bag 4 having one side contacting the spring 3 are embedded in the ink reservoir 1. The flexible bag 4 is connected to a communication hole 5 formed in the lid 2.
In the ink cartridge having the above structure, ink is filled in a negative pressure state through a port (not shown). Due to the negative pressure inside the cartridge, ejection of ink through a printhead (not shown) is prevented when the printhead is not used.
As ink is used, the pressure of the ink reservoir 1 decreases, and thus the negative pressure increases. Further, the flexible bag 4 expands so that the volume of the ink reservoir 1 decreases and the ink reservoir 1 is maintained under a predetermined range of negative pressure. Thus, this provides for ink to be continuously ejected through the printhead from the ink reservoir 1. If the atmospheric pressure greatly decreases (for example, if the ink cartridge is transferred by airplane), the flexible bag 4 contracts such that the volume of the ink reservoir 1 increases, the ink reservoir 1 is maintained under the predetermined range of negative pressure and ejection of ink through the printhead is prevented.
However, the conventional ink cartridge has a complicated structure, and the volume of the flexible bag 4 which serves as a buffer is large. Thus, the ink cartridge with the flexible bag 4 is not suitable for a small ink cartridge, in particular, a small color ink cartridge.
Accordingly, it is an object of the present invention to provide an ink cartridge with a pressure-controlling module having a compact structure.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and/or other objects of the present invention are achieved by providing an ink cartridge with a pressure-controlling module. The ink cartridge includes an ink reservoir in which ink is stored, a printhead through which ink from the ink reservoir is ejected onto a printing medium in a droplet shape, and a pressure-controlling module which is placed in the ink reservoir, by which the ink reservoir is maintained at a predetermined range of negative pressure, and in which a buffer volume to accommodate a rapid volume expansion of the ink reservoir is prepared. The pressure-controlling module includes a body having one opened side, which communicates with the ink reservoir, a guide plate which is placed vertically in the body and moves horizontally according to the pressure variations of the ink reservoir such that the ink reservoir is maintained at a predetermined range of negative pressure, a flexible wall through which the guide plate and the opened side are connected to be sealed and which forms a variable wall depending on the movement of the guide plate, a spring which connects the guide plate to a side facing the opened side, and a vent hole to communicate a space, which is separated from the ink reservoir by the flexible wall, with ambient air.
The foregoing and/or other objects of the present invention may also be achieved by providing a color ink cartridge with a pressure-controlling module which comprises a plurality of ink reservoirs each of which is filled with a predetermined color of ink. Each ink reservoir includes a printhead through which ink of the ink reservoir is ejected onto a printing medium in a droplet shape, and a pressure-controlling module for each ink reservoir which is placed in the ink reservoir, by which the ink reservoir is maintained at a predetermined range of negative pressure, and in which a buffer volume to accommodate a rapid volume expansion of the ink reservoir is prepared. Each pressure-controlling module includes a body having one opened side, which communicates with the ink reservoir, a guide plate which is placed vertically in the body and moves horizontally according to the pressure variations of the ink reservoir such that the ink reservoir is maintained at a predetermined range of negative pressure, a flexible wall through which the guide plate and the opened side are connected to be sealed and which forms a variable wall depending on the movement of the guide plate, a spring which connects the guide plate to a side facing the opened side, and a vent hole to communicate a space, which is separated from the ink reservoir by the flexible wall, with ambient air.